There are numerous automated systems for the handling of empty, flat folded storage bags in preparation for filling with a flowable material. Many include a magazine assembly having a chamber in which bags to be filled are initially stacked, then sequentially removed or fed from the chamber and transported by various means to a filling station. Some systems involve one-by-one removal of bags from the top of a magazine chamber. Others involve one-by-one removal of bags from the bottom of a magazine chamber.
Examples of systems where stacked bags are automatically removed from the top of a magazine chamber include those disclosed in U.S. Pat. No. 3,466,837 (Sturges) granted on Sep. 16, 1969; U.S. Pat. No. 4,970,847 (Gradwohl) granted on Nov. 20, 1990; U.S. Pat. No. 5,050,651 (Hejlesen) granted on Sep. 24, 1991; and U.S. Pat. No. 7,194,849 (Komp) granted on Mar. 27, 2007.
Examples of systems where stacked bags are automatically removed from the bottom of a chamber include those disclosed in U.S. Pat. No. 2,332,187 (Allen) granted on Oct. 19, 1943; U.S. Pat. No. 3,989,073 (Remmert) granted on Nov. 2, 1976; U.S. Pat. No. 4,345,629 (Inglett) granted on Aug. 24, 1982; U.S. Pat. No. 6,705,606 (Summa) granted on Mar. 16, 2004; and Japanese Publication No. JP 7277307A (Sakai) published on Oct. 24, 1995.
Various problems can arise in the operation of such systems.
One potential problem is adherence between adjacent bags. For example, two bags may be held together by a small spot of leaked glue. The strength of adherence may be weak, but nevertheless sufficient to compromise automated one-by-one removal of bags from a magazine chamber.
Another potential problem involves the flatness of the bags. Merely because the bags are “flat folded” does not mean they are flat or will lie in flat planes atop one another when stacked in a chamber. Their surfaces may have some bowing, rippling or other distortion away from planar flatness. Such distortions can compromise reliable separation and dispensing of individual bags from the chamber.
A further potential problem with many known systems is the lack of a suitable operating strategy in the event there is a malfunction in the mechanisms used to transport bags from a magazine assembly to a bag filling station. Even though the magazine assembly may remain serviceable, a failure in the transport mechanism may dictate a complete system shutdown. This problem can arise, for example, in a system like that of Sturges, supra, where bags are gripped and removed from the top of a magazine chamber and, with the same mechanism, are then transported directly to a bag filling station. As another example, it can also arise with a system like that of Sakai, supra, where bags are gripped and removed from the bottom of a magazine chamber and, with the same mechanism, are then transported directly to a bag filling station.
In the case of flat folded valve bags, other problems can arise—for example, the reliable opening of valves to enable filling at a bag filling station. Typically, the mechanism which is used to transport a valve bag to a bag filling station will include a means to open the valve at the time it grips the bag. The transport mechanism then steers the bag with its opened valve over a filling nozzle at the bag filling station. However, if the nozzle encounters a bag with a valve which is incompletely opened, and if the problem cannot be corrected, then the bag has to rejected. In an automated system, it is obviously desirable to minimize the frequency of such occurrences. This requires consideration not only of the mechanism used to open valves but also the manner in which bags are presented to the bag filling station.
As another example in the case of flat folded valve bags, the manner in which the bags are stacked in a magazine chamber can become an issue. The thickness of each flat folded bag typically may not be uniform along the length of the bag. When stacked on top of one another in a magazine chamber, the result can be a stack where the upper bags in the stack progressively become more and more tilted within the chamber as the number of bags is increased—eventually to an unworkable degree which limits the addition of more bags to the stack.
Various aspects of the present invention address the foregoing issues. Generally, there is a need for new and improved methods and apparatus for handling empty, flat folded storage bags, including flat folded valve bags, in preparation for filling with a flowable material. The need exists not only from an overall system point of view beginning with the structure and operation of a bag holding magazine assembly and ending with the presentation of empty bags to a bag filling station, but also in relation to intermediate stages of handling.